A REMOTE-SENSING BASED METHODOLOGY FOR MANGROVE STUDIES IN MADAGASCAR

Despite their environmental and economic significance the exact status and geographical extent of mangrove ecosystems are unknown in Madagas car. For the first time, the deltaic complex of Mahajamba bay has been surveyed, using SPOT 1 and SPOT 2 imagery. An intensive field survey together with complete aerial coverage at a scale of 1:40 000 were use d for the validation of the digital classification. The accuracy of ca rtographic products and of vegetation changes is closely related both to the adopted image processing methods and to the season of satellite data acquisition. The main input of the present contribution is to pr ovide precise descriptions and mapping of the mangroves in Madagascar using high resolution remote sensing technology to assess conspicuous changes. Some conspicuous limitations of satellite data have also been noted. Nevertheless the results can be used for conservation and mana gement purposes.